Bats use echolocation to navigate and hunt, but they also make calls for communication. When a bat is hunting, the proces of catching an insect becomes visible by a so called feeding buzz. Examples of feeding buzzes can be found on the Feeding buzzes page. Calls used for communication can be found on the Social calls page.

The echolocation of bats are a great way to identify bat species, because the calls of each species has it's own specifications. The shape of the call, the peak frequency of the call, the start and end frequency of the call, the call length and the inter-pulse interval can all be important indicators to identify the species you are dealing with. Two great guides for bat identification are "Bat Calls of Britain and Europe" edited by Jon Russ and "Acoustic Ecology of Europan Bats" by Michel Barataud.

Different shapes

Examples

Distribution: rare in all of it's distribution. Vagrant status in the Netherlands with only one sighting in 1993 in Bovenkarpsel, Noord-Holland.

Peak frequency often between 10 to 20 kHz  -  usually qCF calls, sometimes alternated with FM-qCF calls  -  long call length  -   long inter-pulse interval  -  chip-chop sound

Date of recording: 2024-06-06          Recorded by: Magnus Karlsson          Audio file: 911682 (not recorded in the Netherlands)

Distribution: throughout the most of the Netherlands.

Peak frequency often around or just below 20 kHz  -  usually qCF calls, sometimes alternated with FM-qCF calls  -  relatively long inter-pulse interval  -  chip-chop sound

Date of recording: 2024-06-07          Recorded by: Timo Boer          Audio file: 912080 

Distribution: sparsly scattered throughout the whole of the Netherlands, not present in Zeeland and Flevoland.

Peak frequencty often around 25 kHz  -  qCF or FM-qCF calls, sometimes alternated  -  long inter-pulse interval  -  sometimes chip-chop sound

Distribution: sparsly scattered throughout the whole of the Netherlands.

Peak frequency often around 25 kHz  -  usually FM-qCF calls, sometimes qCF calls  -  regular inter-pulse interval  -  no chip-chop sound

Distribution: throughout the most of the Netherlands.

Peak frequency often around 25 kHz  -  usually FM-qCF calls  -  regular inter-pulse interval  -  tapdancer sound

Distribution: Vagrant status in the Netherlands with only three sightings: in 1993 and 1998 nearby Den Helder, Noord-Holland, and in 2003 in Leusden, Utrecht.

Peak frequency often around 30 kHz  -  usually FM-qCF calls, but qCF possible  -  unique frequency band (from 50 kHz to 30 kHz) - irregular pulse rythm

Date of recording: 2021-07-17          Recorded by: Stanislas Wroza          Audio file: 805735 (not recorded in the Netherlands)

Distribution: throughout the most of the Netherlands.

Peak frequency often around 40 kHz  -  FM-qCF or qCF calls  -  dull bubbling sound

Distribution: throughout the whole of the Netherlands.

Peak frequency often around 45 kHz  -  most often FM-qCF calls, but qCF possible  -  dull bubbling sound

Distribution: sparsly scattered throughout the whole of the Netherlands, not present in Flevoland.

Peak frequency often around 55 kHz  -  most often FM-qCF calls, but qCF possible  -  dull bubbling sound

Distribution brown long-eared bat: throughout the most of the Netherlands.
Distribution grey long-eared bat: rare in the Netherlands, but present in Lumburg, the east of Noord-Brabant and the south of Zeeland.

Very difficult to distinguish the two species on their echolocation calls. Click here for a guide. The examples below are from brown long-eared bats.
Peak frequency often between 20 - 30 kHz  -  FM calls  -  calls contain harmonics  -  quiet crackling sound  -  can only be heard within 5 meters

Distribution: very rare in the Netherlands, but mainly present in the south of Limburg and the east of Overijssel. Not present in Flevoland, Friesland, Groningen, Noord-Holland and Zeeland.

Peak frequency often between 30 - 35 kHz  -  FM calls (wiggly-looking)  -  relatively long inter-pulse interval  -  short to relatively long call length  -  dry clicks

Distribution: throughout the most of the Netherlands, less densely in the east and south.

Peak frequency often around 35 to 40 kHz  -  FM calls - high start frequency and low end frequency  -  short to relatively long call length  -  rattle sound

Distribution: scattered throughout the whole of the Netherlands, in particular densely present at the western coast line, Utrecht, Gelderland and Noord Brabant.

Peak frequency often around 45 to 50 kHz  -  FM calls - high start frequency and low end frequency  -  short call length -  rattle sound

Distribution whiskered myotis: sparsly scattered throughout the whole of the Netherlands.
Distribution brandt's myotis: rare in the Netherlands, only present in the east of Overijssel and Gelderland, a small part of Utrecht and the south of Limburg.

Very difficult to distinguish the two species on their echolocation calls.
Peak frequency often around 45 to 50 kHz  -  FM calls  -  very high start frequency possible and low end frequency  -  quiet clicks  -  can only be heard within 5 - 7 meters

Distribution: sparsly scattered throughout the whole of the Netherlands, in particular more densely present in Utrecht and Gelderland.

Peak frequency often around 30 to 50 kHz  -  FM calls  (often convex) -  very high start frequency and very low end frequency  -  short call length  -  very dry sound

Distribution: very rare bat in the netherlands, only more densily present in the south of Limburg and sparsely scattered throughout Overijssel and Gelderland.

Peak frequency often around 50 kHz  -  FM calls  -  very high start frequency and average bandwidht of 90 kHz  -  short call length  - usually too quiet to be detected

Distribution: very rare in the Netherlands, mainly present in Limburg.

No clear peak frequency  -  FM calls  -  very high start frequency and high end frequency (above 40 kHz)  -  short inter-pulse intervals  -  short call length  -  very dry sound

Distribution: very rare in the Netherlands, only present in the south of Zeeland and the east of Gelderland.

Peak frequency often around 32 kHz (FM calls)  -  typically alternates between FM and qCF-FM calls  -  rattling sound similar to castanets

Distribution: Almost totally disappeared in the Netherlands. Most likely to encounter the species in Limburg, but hibernating bats were also found near Utrecht in 1992 and near Den Haag, Zuid-Holland, in 2020 and 2021.

Peak frequency often around 80 kHz  -  FM-CF-FM calls  -  continuous warbling sound

Date of recording: 2025-07-25          Recorded by: Sarah Mahie          Audio file: 1020280 (not recorded in the Netherlands)

Distribution: Currently extinct in the Netherlands. Were only present in Limburg with the last sighting from 1983. In 2019 a bat was found in Steenokkerzeel, Vlaanderen, Belgium.

Peak frequency often around 110 kHz  -  FM-CF-FM calls  -  continuous warbling sound

Date of recording: 2024-05-29          Recorded by: brickegickel          Audio file: 910362 (not recorded in the Netherlands)

New species in the Netherlands?

Bats are flying creatures, so vagrants are not to be unexpected. However, audio recordings often provide not enough proof to declare the presence of a new species.

Distribution: Official sightings in Hermeton-sur-Meuse and Rochefort, Belgium, in 2008 and 2011.

FM calls  -  explosive start on high frequencies  -  no final whack in approach phases - no abs high in cruising phase

Distribution: Official sightings from Brussel, Belgium, in 2012 and 2020.

Peak frequency often around 40 kHz  -  most often FM-qCF calls, but qCF possible  -  calls occasionally have an FM ending -  difficult to distinguish from P. nathusii

Date of recording: 2025-08-10          Recorded by: Paul Dujardin          Location: Roosendaal, Noord-Brabant          Audio file: 368568052

Distribution: A small population is present just across the border near Ahaus, Germany.

Peak frequency often around 35 kHz  -  most often FM-qCF calls, but qCF possible  - somewhat subdued rhythm

Deviations

Bats leaving their roost

Directly at emergence from the roost, echolocation calls are typically short in duration and elevated in frequency and are not typical of free-flying bats (Newson, 2024).

Common noctule leaving it's roost:

Date of recording: 2024-04-28          Recorded by: Dennis Rademaker          Audio file: 920109 

Serotine bat leaving it's roost:

Date of recording: 2024-05-19          Recorded by: Sander Boersma          Audio file: 912051 

Brown long-eared bat leaving it's roost:

Date of recording: 2024-07-13          Recorded by: Boaz van Die          Audio file: 921381 

Common pipistrelle leaving it's roost:

Date of recording: 2024-06-17          Recorded by: Sarah Mahie, Boaz van Die          Audio file: 914381 

Modified echolocation calls

Examples of modified echolocation calls are very rare and so far previous literature written about these calls have not been able to determine the context behind such emissions. They may be communicative, at least to some degree (Middleton et al., 2020).

Hooked echolocation calls of the common pipistrelle:

Hooked echolocation calls of the Nathusius' pipistrelle:

Hooked echolocation calls of the common noctule:

Date of recordings: 2024-08-28          Recorded by: Fabienne Schwab         Audio files:     930849, 930846, 930844, 930842

Hooked echolocation calls of the serotine bat:

Not to be confused with the social calls shaped like walking sticks of the pond bat and the Daubenton's bat. And, perhaps, there is also some similarity to the rare social calls of the serotine bat emitted while in flight that can appear as arches.

Social calls of the Daubenton's bat:

Social calls of the pond bat:

Date of recording: 2024-06-06          Recorded by: Anice Hut          Audio file: 911253 

All recordings are licensed under the following Creative Commons Attribution-NonCommercial-NoDerivs 4.0 license and in courtesy of Sarah Mahie.
All sonograms are screenshots of the recordings imported in the ultrasound analysis software BatExplorer 2.2 (Elekon, Switzerland). 

Bibliography:

- Jon Russ (2021). Bat Calls of Britain and Europe: a Guide to Species Identification. Pelagic Publishing. 

- Michel Barataud (2020). Acoustic Ecology of European Bats. Species Identification, Study of their Habitats and Foraging Behaviour (Anya Cockle-Betian, trans.). Second edition. Inventaires & biodiversité series. Biotope - Muséum national d'Hostoire naturelle.

- Neil Middleton, Andrew Froud and Keith French (2022). Social Calls of the Bats of Britain and Ireland (second edition). Pelagic Publishing.

- Stuart Newson (2024). https://www.linkedin.com/posts/stuart-newson